21102842 has 4 divisors (see below), whose sum is σ = 31654266. Its totient is φ = 10551420.

The previous prime is 21102821. The next prime is 21102853. The reversal of 21102842 is 24820112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 14295961 + 6806881 = 3781^2 + 2609^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5275709 + ... + 5275712.

Almost surely, 2^21102842 is an apocalyptic number.

21102842 is a deficient number, since it is larger than the sum of its proper divisors (10551424).

21102842 is a wasteful number, since it uses less digits than its factorization.

21102842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10551423.

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 21102842 is about 4593.7829726708. The cubic root of 21102842 is about 276.3420547276.

Adding to 21102842 its reverse (24820112), we get a palindrome (45922954).

The spelling of 21102842 in words is "twenty-one million, one hundred two thousand, eight hundred forty-two".